There is one basic guide here https://github.com/adam-p/markdown-here/wiki/Markdown-Here-Cheatsheet
You can create tables by assembling a list of words and dividing them with hyphens ` - ` (for the first row), and then separating each column with a pipe ` | `: |
| First Header | Second Header |
| ------------- | ------------- |
| Content Cell | Content Cell |
| Content Cell | Content Cell |